Guide/Loop Filters

A loop filter is a useful construction pattern that allows one to reliably and flexibly filter gases or liquids by composition, temperature, or germ count, at a low power cost.

Basic Design
The loop filter uses several shutoffs, each linked to a sensor immediately before it and leading into an output pipe, to pipe out the packet of gas (or liquid) that satisfies the sensor's criterion, or loop it back if it satisfies none (a situation that should be avoided) or the appropriate output pipe is blocked or backed up.

The input and output bridge are important in this construction, since they set the direction of flow (counterclockwise in this example) and priority (the contents will loop first before taking more input in).

Advantages
These filters take a minuscule amount of power at 10 W per shutoff currently triggered, essentially making Gas Filter or Liquid Filter with their constant 120W draw obsolete, and can sort by temperature and germ count.

Disadvantages
They are somewhat large with their 3x4 size (of which the 2x4 sensor/shutoff block can't be hidden behind buildings). They take at minimum 170 kg of Refined Metals to set up (20 for auto wire, 100 for shutoffs, 50 for sensors) and require HVAC for gas filtering, Liquid Tuning for liquid, Healthcare for germ versions of either and Advanced Automation for the NOT gate, all of which are advanced research.

A-!A
Using the same setting on both sensors, but preceding one with a NOT gate. This lets one element through pipe A and everything else through pipe B, essentially recreating the Gas Filter or Liquid Filter.

Multi-output
Using more than two sensor+shutoffs to sort out the input. Note that you need to make sure that you have as many outputs as the amount of gases the input consists of.

Gas or liquid sorting
Sort out mixed sources of gas or liquid.

Filtering station
A centralized gas filtering station somewhere in your base will get rid of the pesky packets of Chlorine, Hydrogen, Natural Gas and so on that you have floating around.

Atmosphere adjustment
Fill the room with a specific gas or gas mixture far faster by simultaneously piping the needed gas in through a vent while using a Gas Pump to take the existing mixture and filtering it to pump the needed gases back in.

Disinfection
A liquid reservoir that's situated in a Chlorine atmosphere destroys germs in its liquid, but not instantly. Pipe it back into the tank if the germ count is above zero.

Refinery Coolant
Coolant piped out of the Metal Refinery can be piped back in if it's cold enough, or piped out to get processed (polluted water into water sieve, crude oil into oil refinery or oil cooker, petroleum into plastic or power) or cooled down.